U.S. patent number 11,326,272 [Application Number 16/727,937] was granted by the patent office on 2022-05-10 for mono-crystalline silicon growth apparatus.
This patent grant is currently assigned to GlobalWafers Co., Ltd.. The grantee listed for this patent is GlobalWafers Co., Ltd.. Invention is credited to Chun-Hung Chen, Wen-Ching Hsu, I-Ching Li, Hsing-Pang Wang.
United States Patent |
11,326,272 |
Chen , et al. |
May 10, 2022 |
Mono-crystalline silicon growth apparatus
Abstract
A mono-crystalline silicon growth apparatus includes a furnace,
a support base, a crucible, a heating module disposed outside of
the crucible, and a heat adjusting module above the crucible. The
heat adjusting module includes a diversion tube, a plurality of
heat preservation sheets, and a hard shaft. The diversion tube
includes a tube body and a carrying body connected to the tube
body. The heat preservation sheets are sleeved around the tube body
and are stacked and disposed on the carrying body. The hard shaft
passes through the tube body and does not rotate. The hard shaft
includes a water flow channel disposed therein and a clamping
portion configured to clamp a seed crystal. Therefore, a fluid
injected into the water flow channel takes away the heat near the
clamping portion. A heat adjusting module and a hard shaft of the
mono-crystalline silicon growth apparatus are provided.
Inventors: |
Chen; Chun-Hung (Hsinchu,
TW), Wang; Hsing-Pang (Hsinchu, TW), Hsu;
Wen-Ching (Hsinchu, TW), Li; I-Ching (Hsinchu,
TW) |
Applicant: |
Name |
City |
State |
Country |
Type |
GlobalWafers Co., Ltd. |
Hsinchu |
N/A |
TW |
|
|
Assignee: |
GlobalWafers Co., Ltd.
(Hsinchu, TW)
|
Family
ID: |
69942389 |
Appl.
No.: |
16/727,937 |
Filed: |
December 27, 2019 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20200208295 A1 |
Jul 2, 2020 |
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Foreign Application Priority Data
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Dec 28, 2018 [TW] |
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107147818 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C30B
15/14 (20130101); C30B 15/32 (20130101); C30B
29/06 (20130101); Y10T 117/1032 (20150115) |
Current International
Class: |
C30B
15/14 (20060101); C30B 29/06 (20060101); C30B
15/32 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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103147121 |
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Jun 2013 |
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CN |
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103147121 |
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Jun 2013 |
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CN |
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103938267 |
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Jul 2014 |
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CN |
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105442037 |
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Mar 2016 |
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CN |
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106574392 |
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Apr 2017 |
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CN |
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2942057 |
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Apr 1980 |
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DE |
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2001261482 |
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Sep 2001 |
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JP |
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2001261482 |
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Sep 2001 |
|
JP |
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Primary Examiner: Qi; Hua
Attorney, Agent or Firm: Li & Cai Intellectual Property
Office
Claims
What is claimed is:
1. A mono-crystalline silicon growth apparatus, comprising: a
furnace; a support base disposed in the furnace; a crucible
disposed on the support base, wherein both the support base and the
crucible do not rotate relative to a heating module; and a heat
adjusting module disposed in the furnace and above the crucible,
wherein the heat adjusting module includes: a diversion tube
including a tube body and a carrying body, wherein one end of the
tube body is disposed on the furnace and another end of the tube
body is connected to the carrying body, the carrying body surrounds
the tube body, and the tube body is arranged above the crucible; a
plurality of heat preservation sheets which are annular and sleeved
around the tube body, wherein the heat preservation sheets are
stacked and disposed on the carrying body; and a shaft passing
through the tube body, wherein the shaft does not rotate relative
to the furnace, and wherein a water flow channel is disposed in the
shaft, the shaft includes a clamping portion and at least a part of
the clamping portion is disposed in the crucible to be configured
to clamp a seed crystal, wherein a gas flow channel is disposed in
the shaft, the water flow channel spirals surroundingly around the
gas flow channel, and the clamping portion is adjacent to the water
flow channel and the gas flow channel so that the shaft is
configured to inject flowing water into the water flow channel and
to inject flowing gas into the gas flow channel to take away heat
near the clamping portion.
2. The mono-crystalline silicon growth apparatus according to claim
1, wherein each of the heat preservation sheets has a thermal
radiation reflective rate greater than or equal to 70%, and wherein
only less than 10% of heat at one side of the heat preservation
sheets passes through the heat preservation sheets to another side
of the heat preservation sheets.
3. The mono-crystalline silicon growth apparatus according to claim
1, wherein the shaft is configured to move back and forth along the
axial direction of the tube body with a pulling speed and the
pulling speed is less than or equal to 50 mm/hr.
4. The mono-crystalline silicon growth apparatus according to claim
1, wherein the heating module includes a first heating unit, a
second heating unit, and a third heating unit, and the first
heating unit, the second heating unit, and the third heating unit
are respectively disposed at positions with different heights
corresponding to the axial direction.
5. The mono-crystalline silicon growth apparatus according to claim
4, wherein the first heating unit surrounds and faces toward an
upper half of the crucible, the second heating unit surrounds and
faces toward a lower half of the crucible, and the third heating
unit is disposed under the crucible.
6. A heat adjusting module of a mono-crystalline silicon growth
apparatus configured to be disposed in a furnace, comprising: a
diversion tube including a tube body and a carrying body, wherein
one end of the tube body is configured to be disposed on the
furnace and another end of the tube body is connected to the
carrying body, and the carrying body surrounds the tube body; a
plurality of heat preservation sheets which are annular and sleeved
around the tube body, wherein the heat preservation sheets are
stacked and disposed on the carrying body; and a shaft passing
through the tube body, wherein the shaft does not rotate relative
to the furnace, and wherein a water flow channel is disposed in the
shaft, the shaft includes a clamping portion and at least a part of
the clamping portion is disposed in the crucible to be configured
to clamp a seed crystal, wherein a gas flow channel is disposed in
the shaft, the water flow channel spirals surroundingly around the
gas flow channel, and the clamping portion is adjacent to the water
flow channel and the gas flow channel so that the shaft is
configured to inject flowing water into the water flow channel and
to inject flowing gas into the gas flow channel to take away heat
near the clamping portion.
7. A shaft of a mono-crystalline silicon growth apparatus
configured to be unrotatably disposed in a furnace, comprising: a
gas flow channel disposed in the shaft; a water flow channel
disposed in the shaft, wherein the water flow channel spirals
surroundingly around the gas flow channel; and a clamping portion
adjacent to the water flow channel and the gas flow channel and
configured to clamp a seed crystal, wherein the shaft is configured
to inject flowing water into the water flow channel and to inject
flowing gas into the gas flow channel to take away heat near the
clamping portion.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATION
This application claims the benefit of priority to Taiwan Patent
Application No. 107147818, filed on Dec. 28, 2018. The entire
content of the above identified application is incorporated herein
by reference.
Some references, which may include patents, patent applications and
various publications, may be cited and discussed in the description
of this disclosure. The citation and/or discussion of such
references is provided merely to clarify the description of the
present disclosure and is not an admission that any such reference
is "prior art" to the disclosure described herein. All references
cited and discussed in this specification are incorporated herein
by reference in their entireties and to the same extent as if each
reference was individually incorporated by reference.
FIELD OF THE DISCLOSURE
The present disclosure relates to a crystal growth apparatus, and
more particularly to a mono-crystalline silicon growth
apparatus.
BACKGROUND OF THE DISCLOSURE
A conventional silicon growth apparatus is configured to melt a
solid raw material through heating and to solidify and crystallize
the melted raw material to form a crystal rod. In addition, because
the Czochralski Method (i.e., CZ method) is the primary method used
in a conventional process to manufacture a crystal rod,
conventional mono-crystalline silicon growth methods are also
limited thereto. As a result, development in this field has been
limited, and still has room for improvement.
SUMMARY OF THE DISCLOSURE
In response to the above-referenced technical inadequacies, the
present disclosure provides a mono-crystalline silicon growth
apparatus to improve on issues associated with obstacles against
development in this field.
In one aspect, the present disclosure provides a mono-crystalline
silicon growth apparatus including a furnace, a support base, a
crucible, and a heat adjusting module. The support base is disposed
in the furnace. The crucible is disposed on the support base, and
the support base and the crucible do not rotate relative to the
heating module. The heat adjusting module is disposed in the
furnace and above the crucible, and the heat adjusting module
includes a diversion tube, a plurality of heat preservation sheets,
and a hard shaft. The diversion tube includes a tube body and a
carrying body. One end of the tube body is disposed on the furnace
and another end of the tube body is connected to the carrying body,
and the carrying body surrounds the tube body. A projection area
formed by orthogonally projecting the tube body along an axial
direction of the tube body onto the crucible falls on an inner
bottom surface of the crucible. The heat preservation sheets are
annular and are sleeved around the tube body. The heat preservation
sheets are stacked and disposed on the carrying body. The hard
shaft passes through the tube body. The hard shaft does not rotate
relative to the furnace. A water flow channel is disposed in the
hard shaft, the hard shaft includes a clamping portion and at least
a part of the clamping portion is disposed in the crucible to be
configured to clamp a seed crystal.
Therefore, the mono-crystalline silicon growth apparatus of the
present disclosure includes the effects as follows. The
mono-crystalline silicon growth apparatus includes the hard shaft
which does not rotate relative to the furnace and is disposed in
the furnace. The flowing water injected into the water flow channel
of the hard shaft can take away the heat near the clamping portion
so as to control the heat in the crucible and stabilize a heat
convection in the crucible. Therefore, a crystal growth process of
the seed crystal along the clamping portion can be improved, and a
directional solidification and the crystallization process of the
seed crystal can be effectively controlled. Therefore, by using the
mono-crystalline silicon growth apparatus, a usage rate of the
crystal rod and a production yield are increased.
BRIEF DESCRIPTION OF THE DRAWINGS
The present disclosure will become more fully understood from the
following detailed description and accompanying drawings.
FIG. 1 is a sectional view of a mono-crystalline silicon growth
apparatus of the present disclosure according to an embodiment of
the present disclosure.
FIG. 2 is a partial enlarged view of a hard shaft in FIG. 1.
FIG. 3 is a schematic diagram of the mono-crystalline silicon
growth apparatus forming a mono-crystalline silicon ingot according
to the embodiment of the present disclosure.
FIG. 4 is a flowchart of a mono-crystalline silicon growth method
of the present disclosure according to the embodiment of the
present disclosure.
FIG. 5A to FIG. 5F are schematic diagrams of the mono-crystalline
silicon growth method of the present disclosure according to the
embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
Mono-Crystalline Silicon Growth Apparatus
Referring to FIG. 1 to FIG. 3, an embodiment of the present
disclosure provides a mono-crystalline silicon growth apparatus 100
including a furnace 1, a support base 2 disposed in the furnace 1,
a crucible 3 disposed on the support base 2, a heating module 4
disposed at an outer periphery of the support base 2, and a heat
adjusting module 5 disposed in the furnace 1 and above the crucible
3. It should be noted that the heat adjusting module 5 in the
present embodiment can cooperate with corresponding components
mentioned above, but the connection between the heat adjusting
module 5 and the corresponding components is not limited thereto.
That is to say, in other embodiments of the present disclosure, the
heat adjusting module 5 can be used independently or with other
components.
The furnace 1 includes a furnace wall 11 which is substantially in
a barrel shape and a heat preservation layer 14 inside of the
furnace 1. The furnace wall 11 surroundingly forms an accommodating
space 12 within, and the heat preservation layer 14 is in the
accommodating space 12 so as to maintain a temperature inside the
furnace 1 so that the quality of a crystal rod in the furnace 1 in
a crystal growth process can be ensured.
In addition, a top side of the furnace 1 has a valve port 13 in
spatial communication with the accommodating space 12 so that the
accommodating space 12 can be in spatial communication with the
external environment through the valve port 13. The furnace 1 has a
mounting groove 111 inside which is annular and at an appropriate
height inside of the furnace 1, and the mounting groove 111 in the
present embodiment is at a top side of the heat preservation layer
14, but the present disclosure is not limited thereto.
The support base 2 is preferably made of a graphite material, but
the present embodiment is not limited thereto. The support base 2
is disposed in the heat preservation layer 14 of the furnace 1, the
support base 2 includes a carrying portion 21 which is in a bowl
shape and a support portion 22 which is in a pillar shape, and a
top side of the support portion 22 is connected to a bottom side of
the carrying portion 21.
The crucible 3 can be formed of a quartz material, but the present
embodiment is not limited thereto. The crucible 3 is disposed in
the heat preservation layer 14 of the furnace 1, and the crucible 3
is disposed in the carrying portion 21 of the support base 2. In
addition, in the present embodiment, an outer surface of the
crucible 3 abuts against an inner surface of the carrying portion
21, and a top side of the crucible 3 slightly extends out of the
carrying portion 21 which is in the bowl shape, but the present
embodiment is not limited thereto. The crucible 3 has a crucible
opening 31 at the top side of the crucible 3, and the crucible
opening 31 faces toward the valve opening 13 to be filled with a
melt liquid for being heated. In the present embodiment, the melt
liquid is a silicon melt M.
Therefore, because the crucible 3 softens and deforms easily under
a high temperature, the support base 2 can provide the crucible 3
with a sufficient supporting force to prevent the crucible 3 from
tilting. Moreover, the support base 2 and the crucible 3 in the
present embodiment are limited to not rotate relative to the
furnace 1. That is to say, any support bases or crucibles rotating
relative to the furnace are neither the support base 2 nor the
crucible 3 in the present embodiment.
It should be noted that the furnace 1 is defined to have a central
axis P, and the valve opening 13, the supporting base 2, and the
crucible 3 are all mirror-symmetrical relative to the central axis
P.
The heating module 4 is disposed in the heat preservation layer 14
of the furnace 1 and around the support base 2. The heating module
4 includes a first heating unit 41, a second heating unit 42, and a
third heating unit 43. The first heating unit 41, the second
heating unit 42, and the third heating unit 43 are respectively
disposed corresponding to the central axis P (or an axial direction
of a tube body 511 mentioned below) and at positions with different
heights around the support base 2.
In the present embodiment, the first heating unit 41 surrounds and
faces toward an upper half of the crucible 3, the second heating
unit 42 surrounds and faces toward a lower half of the crucible 3
and is disposed under the first heating unit 41, the third heating
unit 43 is disposed under the crucible, and a projection area
formed by orthogonally projecting the third heating unit 43 onto
the crucible 3 along the central axis P (or the axial direction of
a tube body 511 mentioned below) falls on an outer bottom surface
32 of the crucible 3, but the present disclosure is not limited
thereto. The upper half of the crucible 3 in the present embodiment
refers to a portion extending from the crucible opening 31 downward
to 50% of a depth of the crucible 3, and the lower half of the
crucible 3 refers to a portion extending from the inner bottom
surface 33 upward to 50% of the depth of the crucible 3, but the
present disclosure is not limited thereto.
Moreover, the first heating unit 41, the second heating unit 42,
and the third heating unit 43 can be designed as an annular heating
device or can be a plurality of heating devices arranged annularly,
but the present disclosure is not limited thereto.
The heat adjusting device 5 is disposed in the furnace 1 and above
the crucible 3. The heat adjusting device 5 includes a diversion
tube 51, a plurality of heat preservation sheets 52 disposed on the
diversion tube 51, and a hard shaft 53 passing through the
diversion tube 51. It should be noted that in the present
embodiment, the hard shaft 53 cooperates with the diversion tube 51
and the heat preservation sheets 52, but the connection between the
hard shaft 53 and the diversion tube 51 and the connection between
the hard shaft 53 and the heat preservation sheets 52 is not
limited in the present disclosure. That is to say, in other
embodiments of the present disclosure, the hard shaft 53 can be
used independently or with other components.
The diversion tube 51 includes a tube body 511 and a carrying body
512. The carrying body 512 is disposed on the mounting groove 111
of the heat preservation layer 14 in the furnace 1, and the
carrying body 512 is annular and has an inner hole 5121. One end
(e.g., a top portion 5111 of the tube body 511 in FIG. 1) of the
tube body 511 is disposed on the furnace 1 and extends out of the
valve opening 13, and another end (e.g., a bottom portion 5112 of
the tube body 511 in FIG. 1) of the tube body 511 is connected to a
sidewall of the inner hole 5121 of the carrying body 512. Moreover,
the carrying body 512 surrounds the tube body 511, and the tube
body 511 and the carrying body 512 are both above the crucible
3.
In addition, the tube body 511 of the diversion tube 51 and the
carrying body 512 of the diversion tube 51 cooperatively define a
central axis, and the central axis is preferably substantially
overlapping with the central axis P. That is to say, the axial
direction of the tube body 511 is parallel to the central axis P.
Therefore, a projection area formed by orthogonally projecting the
tube body 511 onto the crucible 3 along the axial direction of the
tube body 511 falls on the inner bottom surface 33 of the crucible
3. Moreover, the tube body 511 is formed of a material which does
not react with crystal growth gas, which is generally stainless
steel, but the present disclosure is not limited thereto.
In the present embodiment, the heat preservation sheets are
preferably in an annular shape and sleeved around the tube body
511. That is to say, the heat preservation sheets 52 are stacked
and disposed on the carrying body 512 and sleeved around the tube
body 511, but the present disclosure does not limit the shapes of
the heat preservation sheets 52. Each of the heat preservation
sheets 52 has a thermal radiation reflective rate greater than or
equal to 70%. Moreover the heat preservation sheets 52 allow only
less than 10% of heat at one side of the heat preservation sheets
52 to pass through the heat preservation sheets 52 to another side
of the heat preservation sheets 52.
More specifically, a number of the heat preservation sheets 52 of
the heat adjusting module 5 is seven, but in other embodiments of
the present disclosure, the number of the heat preservation sheets
52 of the heat adjusting module 5 is greater than or equal to
three. The heat preservation sheets 52 are formed of molybdenum,
but the present disclosure is not limited thereto.
Moreover, the heat preservation sheets 52 have a function of
reflecting thermal radiation and can reflect heat into the crucible
3. In addition, the bottom portion 5112 of the tube body 511 is
connected to the inner hole 5121 of the carrying body 512, and the
heat preservation sheets 52 are stacked and disposed on the
carrying body 512 so that the carrying body 512 and the heat
preservation sheets 52 are outside of the tube body 511. The
carrying body 512 is disposed on the mounting groove 111 so that
the tube body 511, the carrying body 512, and the heat preservation
sheets 52 are disposed above the crucible 3, further forming an
obstruction above the heat preservation layer 14 to effectively
control the heat dissipating through the top side of the heat
preservation layer 14.
The hard shaft 53 is in a strip shape and passes through the tube
body 511 (as shown in FIG. 1 and FIG. 2), and the hard shaft 53
does not rotate relative to the furnace 1. A water flow channel
531, a gas flow channel 533, and a clamping portion 532 disposed at
a bottom side of the hard shaft 53 are disposed in the hard shaft
53.
Both the water flow channel 531 and the gas flow channel 533 can be
injected with a fluid to take away the heat near the clamping
portion 532 mentioned below. In the present embodiment, the water
flow channel 531 can be injected with flowing water and the gas
flow channel 533 can be injected with flowing gas, but the present
disclosure is not limited thereto. In addition, the water flow
channel 531 preferably spirals surroundingly around the gas flow
channel 533 to provide the hard shaft 53 with a better cooling
effect, but the configuration relationship between the water flow
channel 531 and the gas glow channel 533 is not limited in the
present disclosure.
The clamping portion 532 is disposed at the bottom side of the hard
shaft 53, and at least a part of the clamping portion 532 is
disposed in the crucible 3 to clamp a seed crystal 6. In the
present embodiment, the clamping portion 532 is adjacent to the
water flow channel 531 and the gas flow channel 533 so that the
fluid injected into the water flow channel 531 and the gas flow
channel 533 can take away the heat near the clamping portion
532.
In addition, the hard shaft 53 can move back and forth along the
axial direction of the tube body 511 with a pulling speed
preferably less than or equal to 50 mm/hr. When the hard shaft 53
is moving, the clamping portion 532 thereof is maintained in the
crucible 3 and moves correspondingly. The pulling speed of the hard
shaft 53 can be changed according to the requirements of the
crystal growth, and the present disclosure is not limited
thereto.
Therefore, the fluid injected into the water flow channel 531 and
the gas flow channel 533 can take away the heat near the clamping
portion 532 so as to prevent the clamping portion 532 from being
influenced by the heat of the silicon melt M in the crucible 3, can
control the heat in the crucible 3 effectively, and can stabilize a
heat convection in the crucible 3 to maintain a degree of flatness
of solidification between a crystal 7 and the silicon melt M.
It should be noted that the gas flow channel 533 of the hard shaft
53 in the present embodiment can be omitted. That is to say, in
another embodiment of the present disclosure, only the water flow
channel 531 and the clamping portion 532 at the bottom side of the
hard shaft 53 are disposed in the hard shaft 53, and the clamping
portion 532 is adjacent to the water flow channel 531 so that the
fluid injected into the water flow channel 531 can take away the
heat near the clamping portion 532.
Referring to FIG. 1 to FIG. 3, the mono-crystalline silicon growth
apparatus 100 in the present embodiment takes advantages of the
structural design of the heat adjusting module 5 and the
configuration relationship between the heat adjusting module 5 and
other components (e.g., the heat preservation layer 14 of the
furnace 1, the crucible 3, and the heating module 4). That is to
say, the pulling speed and the quality of forming the crystal 7 can
be improved through the addition of the hard shaft 53, where the
fluid in the water flow channel 531 and/or the gas flow channel 533
takes away the heat of surface solidification during the growth of
the crystal 7, the heat conducting from inside of the silicon melt
M to the crystal 7. Therefore, a directional solidification and a
crystallization process of the seed crystal 6 melted near the
clamping portion 532 can be effectively controlled so that the seed
crystal 6 can preferably form the crystal 7.
According to the above, the first heating unit 41, the second
heating unit 42, and the third heating unit 43 of the heating
module 4 are disposed at an outer periphery of the crucible 3.
Therefore, the heating module 4 can provide appropriate heating in
the process of forming a mono-crystalline silicon ingot 8 to
effectively control the growth speed and the growth quality of the
mono-crystalline silicon ingot 8.
Mono-Crystalline Silicon Growth Method
Referring to FIG. 4 to FIG. 5F, the present disclosure further
provides a mono-crystalline silicon growth method which can be
implemented through the mono-crystalline silicon growth apparatus
100, but the present disclosure is not limited thereto. The
mono-crystalline silicon growth method in the present disclosure
includes a preparation step S110, an initiation step S120, a
shoulder-forming step S130, a body-forming step S140, and a
tail-forming step S150.
The preparation step S110 is implemented by providing the
mono-crystalline silicon growth apparatus 100 mentioned above and
disposing the silicon melt M (as shown in FIG. 5A) in the crucible
3 of the mono-crystalline silicon growth apparatus 100. The
specific structure of the mono-crystalline silicon growth apparatus
100 is already described above and will not be reiterated
herein.
That is to say, in the preparation step S110, a stacking charge is
placed in the crucible 3, the crucible 3 is heated to form a
meltdown by the heating module 4 of the furnace 1, and the meltdown
forms the silicon melt M after the heating module 4 appropriately
heats the crucible 3. The silicon melt M can be formed in by an
established method, and will not be reiterated herein.
The initiation step S120 is implemented by solidifying a liquid
surface M1 of the silicon melt M to form the crystal 7 and
horizontally growing the crystal 7 toward a sidewall of the
crucible 3 to increase an outer diameter of the crystal 7.
That is to say, as shown in FIG. 5A to FIG. 5C, the seed crystal 6
is disposed near the clamping portion 532 of the hard shaft 53 and
contacts with the liquid surface M1 of the silicon melt M. A heat
output of the heating module 4 is continuously controlled and
enables the liquid surface M1 of the silicon melt M to solidify to
form a solid-liquid interface M2. The heat near the clamping
portion 532 is taken away by appropriately injecting the fluid into
the water flow channel 531 and/or the gas flow channel 533 of the
hard shaft 53, and as a result, the crystal 7 having the same
crystal structure as that of the seed crystal 6 starts to form on
the seed crystal 6 and the solid-liquid interface M2 of the silicon
melt M. Moreover, a solidifying and crystallization process
includes a neck growth process and a crown growth process.
In the neck growth process, a thermal stress generated by the
contact between the seed crystal 6 and the solid-liquid interface
M2 of the silicon melt M causes dislocations. When a crown starts
to grow, the dislocations disappear (as shown in FIG. 5B). In
addition, in the neck growth process, the seed crystal 6 is pulled
upward rapidly so that a diameter of the crystal 7 during forming
decreases to 4 to 6 mm. More specifically, in the neck growth
process, the dislocations fully disappear through a pulling
technique alternating between fast and slow speeds which is
implemented by fast pulling (e.g., with a fast pulling speed within
a range of 120 to 200 mm/hr) to decrease a diameter of the neck and
slowly pulling (e.g., with a slow pulling speed within a range of
40 to 100 mm/hr) to increase the diameter of the neck. The pulling
technique alternating between fast and slow speeds is implemented
many times so that the dislocations fully disappear.
In the crown growth process, a pulling speed and a temperature are
decreased after the neck is formed so that the diameter of the
crystal 7 is increased gradually to a required size and the crown
starts to form (as shown in FIG. 5C). A diameter increasing rate
(i.e., an angle of the crown) is the most important factor in this
process. If the temperature is decreased too fast, the shape of the
crown becomes rectangular because the diameter increases too fast,
resulting in the dislocations to occur and therefore losing the
crystal structure. Moreover, in the crown growth process, the
pulling technique alternating between fast and slow speeds can be
used to increase a diameter of the crown with the slow pulling
speed (e.g., within a range of 20 to 40 mm/hr). Meanwhile, because
a temperature gradient of a thermal field of the crucible 3 is
small, the heating power of the heating module 4 should be reduced
carefully to effectively control the heat gradient of the thermal
field.
It should be noted that in the starting process, the heat output of
the first heating unit 41 is preferably from 80% to 120% of the
heat output of the second heating unit 42, and the heat output of
the second heating unit 42 is preferably from 80% to 120% of the
heat output of the third heating unit 43.
The shoulder process is implemented by adjusting the thermal field
around the crucible 3 when the outer diameter of the crystal 7
reaches at least 90% of a predetermined value so that the outer
diameter of the crystal 7 reaches the predetermined value and the
crystal 7 is defined as a head crystal, and vertically growing the
head crystal toward an inner bottom 33 surface of the crucible 3.
That is to say, in the present embodiment, the crystal 7 is pulled
upward to form the neck and the crown, after a solidification speed
between the solid-liquid interface M2 of the silicon melt M and the
crystal 7 is stabilized, the crystal will not be pulled nor growing
horizontally, and the head crystal vertically grows downward only
through adjusting the heating module 4 and controlling a cooling
speed of the crucible 3.
It should be noted that in the shoulder-forming step S130, the heat
output of the first heating unit 41 is preferably from 150% to 230%
of the heat output of the second heating unit 42.
As shown in FIG. 5D to FIG. 5F, the body-forming step S140 is
implemented by reducing a total heat output of the heating module 4
so that the head crystal continuously crystallizes to form a first
stage crystal, continuously reducing the total heat output of the
heating module 4 so that the first stage crystal continuously
crystallizes to form a second stage crystal, and reducing the total
heat output of the heating module 4 again so that the second stage
crystal continuously crystallizes to form a third stage
crystal.
That is to say, after forming the neck and the crown, a diameter of
the head crystal is maintained at the predetermined value by
continuously adjusting the pulling speed and the temperature, and a
multi-staged crystal formed by crystallizing for many times as
mentioned above is called a crystal body. In a crystal body growth
process, because the solid-liquid interface M2 of the silicon melt
M and the heating power of heating module 4 gradually decline, a
heat dissipation speed of the crystal body decreases according to a
length of the crystal body.
According to the body-forming step S140 in the present embodiment,
the total heat output of the heating module 4 when forming the
first stage crystal is from 93% to 97% of the total heat output of
the heating module 4 in the shoulder process. In addition, when
forming the first stage crystal, the heat output of the first
heating unit 41 is from 170% to 240% of the heat output of the
second heating unit 42, and the heat output of the second heating
unit 42 is from 180% to 220% of the heat output of the third
heating unit 43.
According to the body-forming step S140 in the present embodiment,
the total heat output of the heating module 4 when forming the
second stage crystal is from 93% to 97% of the total heat output of
the heating module 4 when forming the first stage crystal. In
addition, when forming the second stage crystal, the heat output of
the first heating unit 41 is from 170% to 240% of the heat output
of the second heating unit 42, and the heat output of the second
heating unit 42 is from 180% to 220% of the heat output of the
third heating unit 43.
The total heat output of the heating module 4 when forming the
third stage crystal is from 93% to 97% of the heat output of the
heating module 4 when forming the second stage crystal. In
addition, when forming the third stage crystal, the heat output of
the first heating unit 41 is from 180% to 260% of the heat output
of the second heating unit 42, and the heat output of the second
heating unit 42 is from 180% to 220% of the heat output of the
third heating unit 43.
According to the body-forming step S140 in the present embodiment,
the heat output of the first heating unit 41 is higher than the
heat output of the second heating unit 42, and the heat output of
the second heating unit 42 is higher than the heat output of the
third heating unit 43. Moreover, each of a volume of the first
stage crystal, a volume of the second stage crystal, and a volume
of the third stage crystal is from 23% to 32% of a volume of the
mono-crystalline silicon ingot 8.
It should be noted that in the body-forming step S140 of the
present embodiment, the mono-crystalline silicon growth apparatus
100 preferably receives the heat through injecting the fluid into
the hard shaft 53 so that the crystal 7 grows in the crucible
3.
The tail-forming step S150 is implemented by reducing the total
heat output of the heating module 4 so that the third stage crystal
continuously crystallizes to form a tail crystal, and detaching the
tail crystal from the crucible 3 to form a mono-crystalline silicon
ingot 8 (as shown in FIG. 3) by solidifying the silicon melt M. An
outer diameter of the mono-crystalline silicon ingot 8 is
substantially 90% of an inner diameter of the crucible 3.
According to the tail-forming step S150 in the present embodiment,
a sum of a volume of the head crystal and a volume of the tail
crystal is less than or equal to 30% of the volume of the
mono-crystalline silicon ingot 8.
According to the tail-forming step S150 in the present embodiment,
the total heat output of the heating module 4 when forming the tail
crystal is from 93% to 97% of the total heat output of the heating
module 4 when forming the third stage crystal. In addition, when
forming the tail crystal, the heat output of the first heating unit
41 is from 80% to 120% of the heat output of the second heating
unit 42, and the heat output of the second heating unit 42 is from
180% to 220% of the heat output of the third heating unit 43.
According to the tail-forming step S150 in the present embodiment,
after detaching the tail crystal from the crucible 3 in a crystal
solidifying process, an inner stress of the crystal 7 is reduced as
a result of continuously preserving heat, and the mono-crystalline
silicon crystal ingot 8 is therefore formed by solidifying the
silicon melt M. The mono-crystalline silicon crystal ingot 8 is
then slowly cooled down and taken out of the furnace 1 so that the
mono-crystalline silicon crystal ingot 8 has better growth.
It should be noted that, when implementing the mono-crystalline
silicon growth method to form the crystal 7, the liquid surface M1
(or an interface between the crystal 7 and the silicon melt M) of
the silicon melt M is concave because the temperature gradient is
small such that a stress when the crystal 7 grows is small, and the
quality of the crystal 7 is further increased.
Therefore, referring to FIG. 1 to FIG. 5F, the mono-crystalline
silicon growth apparatus 100 can be used to implement the
mono-crystalline silicon growth method shown in FIG. 4 to FIG. 5F.
In the initiation step S120 of the mono-crystalline silicon growth
method, when the seed crystal 6 contacts the liquid surface M1 of
the silicon melt M to solidify to form the crystal 7, the fluid in
the water flow channel 531 and/or the gas flow channel 533 can take
away the heat near the clamping portion 532 to prevent the clamping
portion 532 from being affected by the heat of the silicon melt M
in the crucible 3. The hard shaft 53 can move forth and back in the
pulling speed along the axial direction of the tube body 511. The
seed crystal 6 at the clamping portion 532 correspondingly moves
forth and back in the pulling speed in the crucible 3 so as to
effectively control a seeding operation and a seeding effect of the
seed crystal 6 at the clamping portion 532.
According to the present embodiment, the temperature of the thermal
field around the crucible 3 can be adjusted according to growth
requirements of the crystal 7 in the crystallization process.
Because the fluid in the water flow channel 531 and/or the gas flow
channel 533 can take away the heat and the heating power (or the
total heat output) of the heating module 4, an outer wall and the
outer bottom surface 32 of the crucible 3 can be appropriately
cooled down so that a bottom side of the crystal 7 is maintained in
a solid state and the temperature of the crystal 7 in a central
region is not affected, which prevents the heat generated by the
heating module 4 disposed at an outer periphery of the crucible 3
from over concentrating at four corners and prevents the crystal 7
growing vertically from sticking to the inner bottom surface 33 of
the crucible. Therefore, the crystal 7 can be prevented from
internally forming an excessive temperature gradient, the inner
stress of the crystal 7 can be effectively controlled so that the
growing speed and quality of the crystal 7 growing vertically can
be controlled effectively to provide the mono-crystalline silicon
ingot 8 with a better growth.
In addition, in the crystallization process, with the co-influence
of the heat adjusting function of the fluid in the water flow
channel 531 and/or the gas flow channel 533 and the heat
preservation function of the heat preservation sheets 52, a
horizontal temperature gradient of the silicon melt M in the
crucible 3 is small so as to control the horizontal crystallization
speed of the crystal 7 to be smaller than the vertical
crystallization speed of the crystal 7 and prevent the clamping
portion 532 from being partially subcooled.
In conclusion, the mono-crystalline silicon growth apparatus
effectively adjusts the temperature around an upper portion and a
bottom portion of the crucible so as to prevent the seed crystal
from melting unevenly in the crystallization process of the
mono-crystalline silicon ingot, and prevent the crystal from
internally forming a temperature gradient that is too large so that
the crystal does not stick to the inner bottom surface of the
crucible, and the inner stress of the crystal can be controlled.
Therefore, the seed crystal goes through the crystal growing
process smoothly, and a crystal growing effect of the crystal and
the quality of the mono-crystalline silicon ingot are improved. As
a result, by using the mono-crystalline silicon growth method, a
usage rate of the crystal rod and a production yield are
increased.
The embodiments were chosen and described in order to explain the
principles of the disclosure and their practical application so as
to enable others skilled in the art to utilize the disclosure and
various embodiments and with various modifications as are suited to
the particular use contemplated. Alternative embodiments will
become apparent to those skilled in the art to which the present
disclosure pertains without departing from its spirit and
scope.
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